1. Field of Invention
The present invention relates to a methylene blue nanoparticle for bioimaging and photodynamic therapy and a use thereof as a cancer therapeutic agent and a contrast agent.
2. Background of Invention
The major conventional therapies for treating cancer, cardiovascular and ophthalmological diseases are surgical operation, radiotherapy, and chemotherapy. Since the conventional therapies for treating cancer such as surgical operation, chemotherapy and radiotherapy have only limited treatment effects and may harm normal tissues as well causing severe side effects, new therapeutic methods such as targeted cancer therapies and photodynamic therapies have drawn attention. The basic concept of photodynamic therapy is the use of the principle that a photosensitizer exposed to light generates singlet oxygen and other active oxygen species. Various photosensitizers have been developed in many countries such as US and Japan, and applied to various kinds of cancer therapies.
Most of the photosensitizers currently used in photodynamic therapy for cancer have disadvantages such as non-specific damage of normal tissues, decomposition into inactive forms, low solubility in vivo, inappropriate interactions with biomolecules, and aggregation among the photosensitizers, and thus show a certain limitation in cancer-specific delivery and low photosensitivity. Therefore, there is a need for an appropriate new delivery system in order to enhance the effects of the therapy.
Photosensitizers for effective treatment require in vivo stability, cancer targeting, low dark toxicity, long wavelength absorption for deep tissue penetration, and high photosensitivity.
Currently, photosensitizers available in Korea include first generation porphyrin-based Photofrin (630 nm, Axcan, Canada) and Photogem (630 nm, Lomonosov Institute of Fine Chemicals, Russia), butthese photosensitzers have a problem with a high supply price (about three million won) per operation.
In addition, although other various photosensitizers have been developed in other countries such as US and Japan, and applied to various kinds of cancer therapies, they still require a lot of time and economical supports until their clinical use.
Meanwhile, methylene blue has been studied as a material for various therapies (Mohr H, Lambrecht B, Selz A. Photodynamic virus inactivation of blood components. Immunol Invest 24(1995):73-85), and has been usually used for medical visualization of lymphatic vessels in a clinical operation such as excision of sentinel lymph nodes. Despite of the use of medical application, however, methylene blue did not clinically used as a photo therapeutic agent and a fluorescent cancer contrast agent with high efficiency.